Electrode Sheet Fluoropolymer Blend for Stable Battery Interfaces
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Solution Overview
Problem
Batteries exhibit poor cycle life and storage life, necessitating improvements in interfacial performance and structural stability.
Innovation Solution
An electrode plate comprising a current collector with a film layer containing multiple fluorinated polymers, where one polymer forms an in-situ gel to enhance solid-liquid interface performance and another polymer improves binding strength through higher cohesive energy density, balancing interfacial reactions and structural stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a single fluorinated polymer is used in the film layer, then the binding strength between active material particles is improved, but the solid-liquid interface performance deteriorates due to insufficient flexibility for in-situ gel formation
Solution Approach 1:
The patent uses a composite of multiple fluorinated polymers with different crystallinities in the film layer. The first fluorinated polymer (higher crystallinity) provides strong binding between active material particles, while the second fluorinated polymer (lower crystallinity) forms flexible in-situ gel at the solid-liquid interface. This composite approach allows both functions to coexist, resolving the contradiction between binding strength and interface performance.
2Strength
If a fluorinated polymer with high crystallinity is used, then the cohesive energy density and binding strength are enhanced, but the molecular chain flexibility decreases, reducing in-situ gel formation capability
Solution Approach 1:
The patent applies local quality by assigning different crystallinity values to different fluorinated polymers in the film layer. The first fluorinated polymer has higher crystallinity (30-60%) for strong binding in specific regions, while the second fluorinated polymer has lower crystallinity (10-40%) for flexibility and gel formation in other regions. This spatial differentiation of material properties resolves the contradiction between cohesive energy and gel formation capability.
3Device complexity
If the crystallinity difference between fluorinated polymers is small, then the material composition is simpler, but the synergistic effect on cycling and storage performance is insufficient
Solution Approach 1:
The patent optimizes the crystallinity parameter of fluorinated polymers to achieve the desired synergistic effect. By controlling the crystallinity of the first fluorinated polymer to be 30-60% and the second to be 10-40%, with a specific difference range (10-30 percentage points), the patent maximizes both binding strength and gel formation capability, thereby improving cycling and storage performance while maintaining reasonable material complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The combination of fluorinated polymers enhances cycling and storage performance of battery cells by stabilizing the solid-liquid interface and improving binding strength, reducing side reactions and swelling deformation.
Implementation Method 1
the crystallinity Xc1% of the first fluorinated polymer is relatively low, and the cold crystallization temperature Tc1°C is relatively low, resulting in greater flexibility of the molecular chain, which is more conducive to the first fluorinated polymer forming an in-situ gel on the surface of active material particles
Implementation Method 2
the second fluorinated polymer has a relatively higher crystallinity Xc2% and a relatively higher cold crystallization temperature Tc2°C, requiring more energy to overcome intermolecular constraints, which is more conducive to enhancing its own cohesive energy density, thereby reducing swelling deformation
Data Source
Figure 1~3
Figure 4~6
AI summary
An electrode plate, a battery, and an electric apparatus are provided. The electrode plate includes a current collector and a film layer disposed on at least one side of the current collector, the film layer including an active material and multiple fluorinated polymers. Among the multiple fluorinated polymers, one fluorinated polymer has a crystallinity denoted as Xc1%, and a cold crystallization temperature denoted as Tc1°C, and among the multiple fluorinated polymers, another fluorinated polymer has a crystallinity denoted as Xc2%, and a cold crystallization temperature denoted as Tc2°C. The multiple fluorinated polymers satisfy: 20% ≤ (Xc2 - Xc1)/Xc1 < 400%, and 30% ≤ (Tc2 - Tc1)/Tc1 < 250%.